Foam generating apparatus



M r h 4, 1958 A. E. WILLIAMS 2,825,413 FOAM GENERATING APPARATUS Filed Sept; 19, 1955 2 Sh eets-Sheet 1 March 1958 H. E. WILLIAMS 2,825,413

FOAM GENERATING APPARATUS Filed Sept. 19. 1955 2 Sheets-Sheet 2 tates FOAM GENERATING APPARATUS Application September 19, 1955, Serial No. 535,217

Claims priority, application Great Eritain September 23, 1%4

9 Claims. ((33. 169i5) This invention relates to foam generating apparatus for fire fighting.

The invention consists in foam generating apparatus comprising two hollow frusto-conical members coaxially disposed one within the other in such a way as to provide an annular passage of increasing width between the walls or" the members and wherein a helical guideway is provided within said annular passage whereby liquid and foam. stabilizer may be expanded into said annular passage and deflected into the interior of the inner frustoconical member at a substantially constant velocity.

According to the preferred arrangement, the outer frusto-conical member is provided with a plurality of holes or perforations and is disposed within a chamber adapted to be supplied with air under pressure whereby water and foam stabilizer may be mixed with air while passing through the aforesaid annular passage, one end of the chamber being provided with an arcuate shaped deflecting member so arranged as to direct the foam into an outlet formed by the inner frusto-conical member.

Preferably means are provided for varying or adjusting the supply of water and foam stabilizer to the annular passage and an open mesh screen is provided at one end of the outer frusto-conical member between said annular passage and said deflecting means whereby the liquid and foam passing through said passage is reversed in direction and caused to pass through said screen twice before reaching said foam outlet.

The invention will be more completely understood from the following detailed description which is given in conjunction with the accompanying drawings in which Figures 1, 2 and 3 are sectional side, end and plan views respectively of a foam generating apparatus constructed in accordance with the invention.

Referring now to these drawings, I construct our improved foam generating apparatus in the form of two truncated hollow conical members 1, 2 which are coaxially arranged one within the other and assembled within a hollow cylindrical body 3 which is conveniently closed at the bottom by a removable cover 4. The two truncated conical members 1, 2 are spaced apart from one another, and are so constructed that the angle between their common axis and the wall of the inner cone 1, is smaller than the angle between such axis and the wall of the outer cone 2, so that an annular passage 5 is formed between the two members, having a cross section increasing in width from one end of the passage to the other. Through the top of the cylindrical body 3 the outer truncated cone 2 projects to a suitable height but its wall is cut helically so as to terminate in a chamber 6 disposed above the aforesaid cylindrical body 3, and provided with an inlet tube 7 for the supply of water and foam stabilizer or foam producing material. This chamber has a removable bolted cover.

Between the two truncated cones 1 and 2 a helical track or guideway 8 is fitted which leads from the feed chamber 6 and has a gradually increasing pitch and increasing width. Water, foam stabilizer, and air are supplied under pressure through the control valve shown on the right Figure 1. This valve has three passages, the upper one 9 of which controls the flow of water to the air foamer, and the central one id of which controls the flow of foam stabilizer which flows from a supply tank by gravity and is induced into the water stream through the passage 11, the rate of flow being adjustable by the screw 12 and ball 13. The lowermost passage 14 which is adjustable by the member 15 is for the admission of air from a suitable blower, and terminates in an outlet pipe 16 which is connected by any suitable means to an inlet 17 in the wall of the cylindrical body 3, while the upper passage 9 terminates in an outlet pipe 18 which is connected by a union member 19 to the inlet 7 leading to the chamber 6. Each of the three passages in the control valve passes through a plug cock or throttle. The upper plug 29 for pressure water has a squared end on its shank to receive the operating handle. At the lower end of the plug a transverse rectangular section bar is formed which is arranged to fit into a slot provided in the top of the plug of the middle cock 25 (for foam stabilizer) so that the rotation of the upper plug causes the middle plug to move with it. A light spring is arranged between the upper and middle plug to maintain the middle plug in proper contact with the body and keep it fluid tight.

Similarly on the lower end of the middle plug a transverse rectangular section bar is provided which engages a slot on the upper side of a cylindrical throttle 26 (for air under pressure) so that this throttle also moves in unison with the two plugs above it. The positioning of the porting in the two plugs 20 and 2S and the throttle 25 is such that they blank ofi' the passageways simultaueously. The passageway in the upper cock and the throttle are of the straightway type. That of the middle plug has an entry at the side at to the discharge so that it is possible for the feed to be taken from either side of the body as may be desired. Within the cylindrical throttle 26 which is machined inside and out, a second cylindrical throttle is provided. This can only be operated by the movement of a special handle 27 mounted on the lower end of the assembly. This handle re-' strained from movement by a ratchet device 23 so that it can be moved and locked in any desired position. The function of the inner throttle 15 is to provide means of partially restricting air flow to suit the expansions of the foam to be produced in the generator. Similarly the adjusting screw 12 can be set to limit the movement of the non-return ball valve 13 from its seat and thereby set the quantity of flow of foam stabilizer to the desired percentage of the water flow. The cock 20 is intended to be opened fully with a 90 rotation from the closed position. This movement will be followed by the plug 25 and the cylindrical throttle 26 and their ports will also be fully opened. The adjustments of screwed plug 12 and inner throttle 15 being used to set the quantities of foam stabilizer and air respectively so as to produce foam of the required quality.

The ball valve setting device and non-return valve are so arranged as to prevent water under pressure from flowing back into the foam stabilizer tank should the discharge from the generator become obstructed when the cock 20 is opened.

The device is provided with a lubricator 28 and alternative side entry connections for foam stabilizer 29.

With this arrangement, water and foam stabilizer is fed through the inlet 7 tangentially against the inner face of the outer truncated cone 2 in the helical passageway and due to its velocity, centrifugal action maintains the liquid against the wall of the outer cone as it proceeds maintained said; space sowas to form .globule's'of foam.

7 3 downward. Air under suitable pressure is fed through the inlet 17 into the'outer cylindrical body' 3,v and passes 1 into the passageway 5 between the truncated conesl and l '2, through a plurality ;of v holes or perforations formed in r the'wallof the outer truncated cone 2' so that this will 7' puncture the water and 'foam stabilize'r'solution and intimately with theliquid to form globules. Any-foam formed "will; due to its lesser'density, be displa cedrto-v rwards-the'outer' wall of the inner truncated cone 1 and V the-liquid remaining will; due to its greater density, continue to passalong the inside f the outer truncated cone 2;" The lowerend'of the assembly is covered with a wire air under pressure into said film of mixture its passage throughs'aidspaee was to form globules orfoan'iz V 3. Foam generating appa'ratu's for fire fighting; 'comr prising a hollow chamber, two hollow frustorconical meme bers disposed one within the other within said chamber so as to provide an annular spacegbetween said members mesh screenlzl which is held in place by a hemispherical i or other a-rcuate shapedbase plate :22, having abehtral:

V pillar -so that as-theemulsion and foamissue-ifro m-th? base of the 'annular passageway it is constrainedto p'ass mira e-newer: mesh;screen 21 a'nd due to the shape of the base is reversedrapidly in direction causing sufficient turbulence to effect an intimate forming of thefoam; rwhichapasses backthrough the wire mesh screen "215mm thelinteriorioflthe inner-truncated cone 1 and rises to the discharge outlet 24v to which suitable connections maybe-- made...

Thus-by meanscf this arrangement, the expanding vo1- umeof ,thezf ormed'foam may be accommodated as it'pro ceedsgdow'nrtherannular passage betweenthe two truncated cones, and an,:output-jof constantvelocity may thus .be-

f Moreover, by, regulating the .air. and water-supplied both thequantityand; the expansion of the foam generated nerator s 'nedt 7 said' space increasinginwidth iirom one end totheother of said members; the outer one of which -h asa perforated 'wall, means for.introducing amixture of liquidand,foann; r

stabilizer tangentially into saidi annula ispacenear to the: i 1

narrow end thereof so as'to maintain by ntrifugal force 7 p a film of mixture ontheewall-of-saidouter}mernber; -a

membs sii -j helical guideway dispdsedbetweensaid trolling the 'r'novem e'nt ofq s'aid mix I passage through said space; and'means for introducing; air under pressure;'through the perforated-wallet saidouter member into'said film of mixturejdurjn'g itsgpassa'ge v through said space so as totorfli r globules of fff oani; I

V can be'varied up to the limit of the outputfor which the;

-The area ofthe'anuulusjbetween the truncated cones V 1 and .12 atthe base-of the latter is substantially equal tothe areaof thebaseof the inner truncated cone 1.-

The apparatus is conveniently constructed of mild steel sheet'; or; other suitable metal suitably protected against corrosion and a drainage plug '25 is preferably provided ,7 The apparatus ;may be built in any desired size toproduce' any required output of foam, or alternatively a plu rality 0t units maybe grouped and used eitherindepend entl y' or together as may berrequired to' give varying out pnts of foamf Y r The apparatus maybe used at any convenient pressure which.may within wide limits but whichwould ,prgbablyfliesdmewherebetween? lbs per sq. inch and V we a r insza ratus o efi n a posedjone vvithinfthe other, in such a way as to provide an'annularjspace betweenrthe walls of the members, said a space increasing in width from one end tothe other/of said members, means forfintroducing a mixture of liquid 7 means; for- ;controlling the -movement -of--said mixture-f throughsaid space,jmeans forintroducing airunderilaresmembenf and Jan open -mesh--gscreen disposed jbetweene prising itwo hollow trusto-cfonical-.rnembersrcoaxially dis j and .foam stabilizer tangentially into said annular space at thevnarrow endv thereof, so as; to direct, and maintain themmturea'gaimt the wall of said outer member, guide means for controlling the, movement of saidQmiX ture 1 through said space andimeans for. introducing, air under pressure: into. saidmix'ture during its rmovement through 2. Foam generating apparatus for firefighting comprisinggtvvo'ho'liovv frusto-conical memberscoaxially disposed' onewithini thelother'in such away as to provide an an-' 'nular space betweenthe walls of-said members, said'space increa'singin width from one 'end to the other of said bil z r an ntial i q S d nnu ar ilagea wi narrow and the sp r oa l-maint i ib c n i ug i s.filifib rmiat e.cnrt r b aid ut member; ihe iqa n ea d spo ed b t n Sa emb s it q lill he mo emen of said x ur and d tefie l P3 .S h-rough' said space and means for introducing i "members means for introducing a nintureeof liquid; and

' end ,to.theother of said members the outeroueof whicli' 4. Foam generating appa ratus posed one within the other in such"arvay asfto' provide an annular sp aceibetween the walls'of the memberslsaidf space increasin in width; from; one end to the other of" said members, means for-introducing a-mixtu're ornq n and foam-{stabilizer tangentially into "said annulap'spacei at-ithenarrowcnd-thereofso as to direct;andimaintain* the mixture-against the wallfof said outer'me nbe'r; guide means for controlling themov'ementrofsaid 'mixtnre 7 through said space means forintrodu'cing air'under presf sure into said-'mixt'nreduring its movement=throughsaid sp'acesq as to forni globules-pf foam; and nieans fordeflecting the -foain so--forrned into the interior of said' i',

inner memben 7 V "5.- Foam generating apparatti's forijfire fightingflc'mprising-two hollow 'fr usto-conical members? coaxially-ldis s po sed one within theother' in such 'a wayfas to-pro'videj r anannular spacebetween thewalls of -the-members,said f:

space increasing in width fronr one end to the other pr;

'said members m eans forintroducing a niiitureof-liquid 1; r

andfoam stabilizentangentially into; said arinular space;-

at -the narrow end thereof so as to direct a'nd mai tain; 1 i

the mixture ag ainst th'e wall of said outer-member; guidersure into .said mixture duringlits movement through said space sodas to form globules of:foam, means tor defl'ec t ingl the-steam so formed into the interior? of said inner saidaannu'lar: spacel and; s aid j'defle'etinga means whereby the liquidiiandafoam passing ithroughfsaid -annular spaoe is=forcedthroughgsaidrgscreengbefore reachingtheinterioi v of said inner member.'-

6; Foam generating V prising; :a hollow chamber; twoahollovvfrusto-conicah 1 members disposed one within the other within"saidichain her. soras. to provide' an annular spaces-betwejen thewall of said members, :said spaceincreasingin-width fromon has a perfo ratedrwall, means; for introducing? a mixture of liquid'eand; foam? stabilizer tangentially'i into said annularv-a space near; to. .theanarrciw Send thereof so as -to maintain by centrifugal-force a filmEofmixture onthevwallgoft'said a r outer membergzaa helicalrguideiway .disposedrabetween' saidi;

members for controlling-r the movementiof "said mixture and directing 'its passage throughrsaidrspace; andimeans r forgintroducing' under pressureVthroughi the-perforate h wallj of ,saidioutenzmemben into; 7 saidJ filmE 1 of; mixtureduring its; passagelthrough -saidz:-.space soi asato form; I

fo'rfire fig'hting pir -Q; 7 ing' two hollow frusto-conical' lmembers coaxially disapparatus-tori fire".fightingl;com-

Y v V 7. Foam generating apparatus for fire fighting as claimed in claim 6, wherein said arcuate shaped deflecting member is of hemispherical form and said open mesh screen is arranged to cover the outlet from said annular space and the inlet to the interior of said inner member whereby the liquid and foam is reversed in direction and is caused to pass through said screen twice before entering the interior of said inner frusto-conical member whereby suflicient turbulence is produced to eifect an intimate forming of foam.

8. Foam generating apparatus for fire fighting as claimed in claim 1 and comprising valve means for adjusting the supply of liquid and foam stabilizer to said annular passage, said valve means having three passages for controlling respectively the flow of liquid, foam stabilizer and air, adjustment means being provided whereby the quantities of air and foam stabilizer may be varied independently with respect to the flow of liquid so as to vary the quantity of foam produced.

9. Foam generating apparatus for fire fighting as claimed in claim 1 and comprising valve means for adjusting the supply of liquid and foam stabilizer to said annular passage, said valve means having three passages for controlling respectively the flow of liquid, foam stabilizer and air, adjustment means being provided whereby the quantities of air and foam stabilizer may be varied independently with respect to the flow of liquid so as to vary the quality of foam produced.

References Cited in the file of this patent UNITED STATES PATENTS 214,090 Bott Apr. 8, 1879 515,528 McGahan Feb. 27, 1894 1,017,585 Pattin Feb. 13, 1912 1,874,209 Schnabel Aug. 30, 1932 2,003,184 Friedrich May 28, 1935 2,138,133 Betzler Nov. 29, 1938 FOREIGN PATENTS 450,460 Italy July 21, 1949 491,838 Great Britain Sept. 9, 1938 917,765 Germany Sept. 9, 1954 

